A physical model of an irrigation border (bay) is constructed and tested. Equations are developed which describe the profile of the water advancing down the border, the rates of advance, and recession after the inflow is cut off, in terms of inflow, infiltration, slope, and surface roughness. Where possible these equations are simplified to a form more suitable for use in design. An illustrative analysis is done to determine correct inflows and cutoff times needed to uniformly irrigate to a desired depth.